I don't have the pixel C, but I was told that there are those issues.
On the android tv, vulkan isn't faster than GL either. We're usually bottlenecked by the PPC JIT.
Also, don't try to get rid of 10W in a tablet
If you want a bit more technical answer:
The pixel c uses the binary blob of nvidia, but with the open source nouveau kernel driver.
GL / Vulkan driver quality is usually given by the user space part, so here the blob.
Power management is done in the kernel, so maybe there are some issues with reclocking
On the android tv, vulkan isn't faster than GL either. We're usually bottlenecked by the PPC JIT.
Also, don't try to get rid of 10W in a tablet
If you want a bit more technical answer:
The pixel c uses the binary blob of nvidia, but with the open source nouveau kernel driver.
GL / Vulkan driver quality is usually given by the user space part, so here the blob.
Power management is done in the kernel, so maybe there are some issues with reclocking